Applied Potential Tomography (APT) is a noninvasive imaging tool that can be used in combination with multiple heating modalities to monitor hyperthermia. Hyperthermia, the use of heat or treat cancer, has been plagued by the inability to recover complete temperature fields during treatment, since the measurement of temperature by a limited number of discrete thermometric probes allows, at best, only an inference of the complete temperature distributions. Though the insertion of many sensor could alleviate the problem, this is highly invasive. Use of a noninvasive imaging method such as APT to monitor thermal dose would greatly reduce the risk of treatment-related infections and other complications, and be less traumatic for patients. Additionally, comparison of pre and post treatment electrical conductivities in the heated region may predict treatment outcome. Thus, APT could potentially be used to simultaneously monitor temperature fields and therapeutic response. The development of an APT system for real-time monitoring of conductivity changes during hyperthermia will require the formation of fast reconstruction algorithms capable of crating accurate two dimensional and three dimensional reconstructions. In addition, rapid data acquisition system must be constructed. The purpose of this work is to further develop, improve, and use APT as a method to monitor thermal dose in inhomogenic phantoms. This work will involve algorithm development, numerical simulations, design and constructions of an optimized APT system, and experimental verification in phantoms. It is hypothesized that accurate APT images can be obtained and processed in real-time by combining advanced data acquisition and signal processing with a reconstruction algorithm based on mathematical projection operations, and that changes in complex broad band conductivity distributions can be obtained in arbitrary geometries with such an APT system,. Numerical simulations and phantom experiments will be used to test these hypothesis. It is hoped that this work will provide a strong foundation for future clinical and experimental applications of APT.